The present invention relates to a hub device for preventing liquid leakage, and more particularly, concerns a hub suitable for use in a catheter placement unit which includes a catheter tube for insertion into a patient, the hub being particularly useful in preventing blood from leaking into the catheter placement unit.
Catheter placement units are employed for a variety of purposes, including the administration of liquids into the bloodstream, monitoring the central venous pressure and the like. A well-known and widely used technique for utilizing a catheter placement unit includes the use of an introducer catheter to which the catheter placement unit is connected; the catheter tubing from the placement unit is then slid through the introducer catheter and on into the vein or other body tissue of the patient. Although, in most cases, there is very little clearance between the outside surface of the catheter tubing and the inside surface of the introducer catheter wall, this clearance oftentimes causes problems.
For instance, inasmuch as both the introducer catheter and the catheter tubing of the catheter placement unit are both inserted into the vein of the patient during various medical procedures, the venous pressure may cause blood to rise into this clearance space between the two catheters. Once this happens, the blood may travel through this clearance space and eventually out of the connecting hub arrangement whereupon the blood then will leak onto the patient or surgical coverings. Some catheter placement units have recognized this problem and have successfully overcome this undesirable leakage. The catheter placement unit described in U.S. Pat. No. 3,825,001 includes an elastomeric diaphragm in the fitting of the catheter placement unit which tightly engages the outer periphery of the tubing. Thus, a seal is provided to prevent the leakage of blood between the catheter tubing and the introducer catheter. However, although the device described in this patent is functionally successful, the structure of the placement unit fitting is somewhat complicated and includes a number of components which may tend to add expense to the device.
Another catheter seal device is described in U.S. Pat. No. 3,970,089. This device includes an elastomeric member with a lumen therethrough, the elastomeric member located in a chamber inside a hollow rigid body. By distending the elastomeric member to constrict the lumen through which the catheter is passed, a seal is formed to prevent egress along the interface between catheter and the innermost surface of the elastomeric member. Various techniques of distending the elastomeric member are disclosed, including admitting air or other inflating fluid to a toroidal bladder which becomes progressively distended, and presses against the catheter to effect the seal. This type of sealing device is also somewhat complicated and lacks the simplicity of design, inexpense of manufacture and functional convenience in order to be compatible with the hub on a catheter placement unit. Accordingly, improvements in sealing the annular space between concentric catheter devices through which blood or other liquids may flow are still being sought. The present invention is directed to such improvements.